4.1 Roman Numerals & Chord Function

Harmonic function

Chords group into three functions: tonic (I, vi — stability/home), predominant (ii, IV — motion away), and dominant (V, vii° — tension pulling to tonic).

Typical progression

A common functional flow is tonic → predominant → dominant → tonic (I–IV–V–I or I–ii–V–I). The dominant's tension resolves back to the tonic.

Roman numeral analysis

Roman numeral analysis labels each chord by its scale degree and quality within the key, showing how harmony moves and functions rather than just naming pitches.

Key terms

Tonic function

I, vi — stability, home

Predominant function

ii, IV — motion away from tonic

Dominant function

V, vii° — tension pulling to tonic

Functional flow

T → PD → D → T

Roman numeral analysis

labels chords by scale degree and quality

Try an AP-style question

Which chords typically serve a predominant function?

1. ii and IV
2. V and vii°
3. iii and I
4. I and vi